1. Field of the Invention
This invention relates to modern vibration dampers, particularly for motor-vehicles, comprise a valve unit which is used for operationally modifying the damping behaviour, e.g. by providing a bypass for a fluid flow path through which a damping fluid and more particularly a damping liquid flows in response to relative movement of a piston rod and a cylinder.
The valve unit can be accommodated within a side-tube of a container tube.
2. Background Information
Vibration dampers of this type are known e.g. from German Publication DE-OS 34 34 877 Al corresponding to U.S. Pat. No. 4,650,042.
According to these publications, a tube section for accommodating a damping valve unit is welded to the radially outer circumferential surface of a container tube of an oscillation damper. When welding the tube section to the container tube it is unavoidable that the tube section is submitted to deformations and that therefore the tube section must be after the welding operation submitted to time-consuming and expensive after treatment operations. The performance of these after treatment operations is very cumbersome, as the unit obtained by welding the tube section to the container tube must be aligned with respect to the after treatment machines such that the inner surface and the outer surface of the tube section are concentric with respect to each other and more particularly as to avoid angular misalignment of these surfaces and excentricity of these surfaces.